The invention is broadly concerned with seals for containers of the type normally utilized in a kitchen environment for the storage of foodstuffs.
The seals of particular concern are adapted to snaplock to the rims of plastic food containers with the containers and seals themselves formed of an appropriate synthetic resinous material, for example polypropylene.
A principal goal of such seals is to hermetically close or seal the container while at the same time provide convenient access to the container contents. As such, the seal or lid, at its most practical, must easily mount to the container, completely seal the container when mounted, and be easily and conveniently removed from the container.
However, when providing an airtight closure, pressure differentials that develop between the interior and the exterior of the container during the mounting of the container tend to disrupt the effectiveness of the seal and the ease of applying the closure. Similarly, a release of the seal can also be inhibited by the pressure differential, particularly when a lower pressure exists within the container. Attempts have been made to alleviate the various pressure differential problems by the provision of venting systems.
A further problem arising from sealed plastic lids which closely conform to the container rim peripherally thereabout, is how to easily remove the lid, particularly in those situations wherein neither the container nor the lid provide a convenient grasping means. Conventionally, the lid is peeled upward about the periphery of the container rim, requiring the use of two hands and possibly an awkward tipping of the container.
Various proposals have been put forth for a pivoting or rocking release of the seal. However, little has been developed in the way of practical systems for providing, in a single seal, a cooperative combination of features which result in a seal combining superior sealing capability with practical and efficient means to both mount and remove the seal.